A device in thermoforming

Abstract: The invention relates to a device in thermoforming, from a thermoplastic material sheet, an opening arrangement of the type which is formed into a pouring spout (7). In this instance, use is made of an outer closure portion (6), a screw cap, as mould in the thermoforming process. The device includes a forming tool (4) and a tube (5) for advancing the outer closure portion (6), and a spacer ring (9) lying outside the advancement tube (5), and manufactured from a resiliently yieldable material. In such instance, a neck (14) is created between the upper side (2) of the package and the outer closure portion (6).

Description: TECHNICAL FIELD The present invention relates to a device in thermoforming, from a thermoplastic material sheet, of a pouring spout which is intended to be surrounded by an outer closure portion, the device including a forming tool wherein the closure portion is included, and a tube for advancing the closure portion. BACKGROUND ART The following method for thermoforming an opening arrangement is previously known from, for example, Swedish Patent Application No. SE-9100921-7. The method entails forming, from a sheet of thermoplastic material, a pouring spout which is surrounded by an outer closure portion, a so-called screw cap. The thermoplastic material sheet may comprise the entire upper side of a package which otherwise consists of a packaging laminate with a core of paper or paperboard to which are laminated different layers, of which the outermost is thermoplastic. The package may be of round or square cross section. The thermoplastic material sheet may also consist of a minor portion, covering a cut-out section from a conventional laminate package, so that it is fixedly welded in place against the inside of the laminate package consisting of thermoplastic material. Such a package may, for example, be a so-called gable top package. On one of the above package types which is finished inasmuch as it consists of side walls and an upper panel or wall, a pouring spout is formed in the upper panel. A forming tool is passed through the as yet uncompleted bottom of the package, and from the upper side of the package, an outer closure portion is lowered, this closure portion being a so-called screw cap which serves as a mould for forming the pouring spout. When the pouring spout has been formed in this manner, the upper portion of the pouring spout is fixedly sealed against the inside of the outer closure portion and, in such instance, the outer closure portion - the screw cap - may readily fasten to the plasticized thermoplastic sheet, so that opening of the package is impeded. OBJECTS OF THE INVENTION One object of the present invention is to make possible sealing of a pouring spout to an outer closure portion without the outer closure position fastening to the plasticized thermoplastic layer which constitutes the upper side of the package. A further object of the present invention is to create a space between the lower threads of the pouring spout and the upper side of the package. SOLUTION These and other objects have been attained according to the present invention in that the device of the type described by way of introduction has been given the characterizing feature that one end of the advancement tube is provided with an external spacer ring. Preferred embodiments of the present invention have further been given the characterizing features as set forth in the appended subclaims. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS One preferred embodiment of the present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 shows, partly in section, the placing of the device according to the present invention, on thermoforming of an opening arrangement; and Fig. 2 shows a spacer ring. DESCRIPTION OF PREFERRED EMBODIMENT That opening arrangement in connection with which the device according to the present invention is employed may be applied to different package types. One such package type consists of side walls 1 of a laminate with a core of paper or paperboard to which is laminated an outer layer of thermoplastic, the package type being further provided with an upper panel or wall 2 wholly consisting of thermoplastic. Other package types are conventional gable-top packages or parallelepipedic packages in whose upper wall a field has been cut out which is covered from the underside by a thermoplastic layer. Regardless of package type, the opening arrangement is produced in a similar way. The as yet unfinished package (which is still open at the bottom) is mounted on a mandrel 3 and a forming tool 4 is inserted via the bottom of the package. At the same time, an advancement tube 5 is moved towards the upper side 2 of the package, this tube being intended to advance to the opening arrangement an outer closure portion 6. The outer closure portion 6 is employed as a mould for thermoforming a pouring spout 7 which is formed from the thermoplastic material layer constituting the upper panel or wall 2 of the package. Fig. 1 shows, partly in section, the upper region of a packaging container of that type which consists of side walls 1 of a packaging laminate to which is sealed an upper panel or wall 2 of thermoplastic. The packaging container (which is open at its lower end) is mounted on a so-called mandrel 3 and a forming tool 4 is inserted inside the package for forming the pouring spout 7 proper of the opening arrangement. An advancement tube 5 abuts against the upper side 2 of the package, a pusher 8 being disposed within the tube. The advancement tube 5 is intended to advance, to the upper side 2 of the package, an outer closure portion 6 wherein the pouring spout 7 is formed. The pusher 8 fixedly retains the outer closure portion 6 against the upper side 2 of the package during the thermoforming process proper. A spacer ring 9 is disposed on the lower region of the advancement tube 5. In the preferred embodiment, the spacer ring 9 is produced as a part of a tubular portion 10 lying outside the advancement tube 5. The upper end of the tubular portion 10 is provided with a bead 11 which rigidly engages with a corresponding groove 12 in the advancement tube 5. The innermost diameter of the spacer ring 9 is slightly less than the smallest diameter of the advancement tube 5 and that edge which, in such instance, projects in towards the centre of the advancement tube 5 fixedly retains the outer closure portion 6 during the thermoforming process proper. The preferred embodiment of the spacer ring 9 with its tubular portion 10 is shown in Fig. 2 in its entirety. Of course, the spacer ring 9 may also be produced by other means, without the outer tubular portion 10 lying outside the advancement tube 5. Thus, a spacer ring 9 may, for example, only comprise a circular portion fixedly secured to the lowermost end of the advancement tube 5. As shown in Fig. 1, the upper thermoplastic wall 2 of the packaging container has been formed into a pouring spout 7 in that the forming tool utilizes the outer closure portion 6 as a mould. After completion of the thermoforming of the pouring spout 7, the outer closure portion 6 is moved by means of the pusher 8 out from the advancement tube 5 in order to remain in place on the pouring spout 7 formed in the closure portion 6. In such instance, the spacer ring 9 must give way so that the outer closure portion 6 may pass through the diameter which is tighter in relation to the advancement tube 5. In such instance, the spacer ring 9 is ideally produced from a resiliently yieldable material such as, for example, rubber. Rubber also possesses the quality that, during the thermoforming process, it seals against that neck 14 which is formed between the upper side 2 of the package and the outer closure portion 6 Once the outer closure portion 6 has been moved out of the advancement tube 5, the forming tool 4 is withdrawn and the outer closure portion 6 is sealed against the upper wall 13 of the pouring spout by ultrasonic sealing. This seal is intended to be broken on opening of the package. Thereafter, the thus almost finished package is stripped from the mandrel 3, filled and bottom sealed to form a finished packaging container. On opening of an opening arrangement which has been manufactured using a device according to the present invention, the upper wall 13 of the pouring spout 7 which is sealed to the inner portion of the outer closure portion 6 is broken. On reclosure of the opening arrangement, the neck 14 which had been formed by employment of the spacer ring 9 allows the outer closure portion 6 to be screwed in more tightly and thereby create a more reliable and tighter reclosure. As will have been apparent from the above description, the present invention realises a device which permits improved production of the opening arrangement so that the outer closure portion does not run the risk of fastening against the upper wall of the packaging container. By the employment of the device on thermoforming of the opening arrangement, a neck will be also be formed which, on reclosure of the package, permits a more reliable and tighter reclosure of the package in that the outer closure portion can be screwed in place more tightly. The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the scope of the appended Claims.

Claims: A device for thermoforming, from a thermoplastic material sheet, a pouring spout (7) which is intended to be surrounded by an outer closure portion (6), the device including a forming tool (4) and a tube (5) for advancing the closure portion (6), said closure portion (6) being included within said tube (5), characterized in that the lower region of said tube (5) is provided with an external spacer ring (9), said spacer ring (9) projecting in towards the centre of said tube (5). A device as claimed in claim 1, characterized in that said spacer ring (9) provides a neck (14) between the upper side (2) of a package and the outer closure portion (6). A device as claimed in claim 1 or 2, characterized in that said spacer ring (9) fixedly retains the outer closure portion (6) during the thermoforming process, thus prevents the fastening of the closure portion (6) onto the upper side (2) of the package. A device as claimed in one of the preceding claims, characterized in that said spacer ring (9) is manufactured from a resiliently yieldable material. A device as claimed in claim 4, characterized in that said spacer ring (9) is manufactured from rubber. A device as claimed in claim 5, characterized in that said spacer ring (9) seals against said neck (14) during the thermoforming process. A device as claimed in one of the preceding claims, characterized in that the spacer ring (9) constitutes a part of a tube (10) lying outside said tube (5). A device as claimed in claim 7, characterized in that the innermost diameter of said spacer ring (9) is slightly less than the smallest diameter of said tube (5). A device as claimed in claim 7 or 8, characterized in that said tube (5) is provided with a groove (12), extending circularly about said tube (5), in which a bead (11) being provided at said tube (10) of said spacer ring (9) rigidly engages.

Inventors: BENGTSSON JOERGEN, BENGTSSON, JOERGEN, Bengtsson, Jörgen
Applicants: TETRA LAVAL HOLDINGS & FINANCE, TETRA LAVAL HOLDINGS & FINANCE SA
Application year: 1994
Main classification: B29C51
IPC codes: B29C65, B29C49, B29C51, B65D43, B29L22